Electromagnet



Patented June 15, 1943 ELECTROMAGNET Marion 8.. Winkier, Chi go, Ill. Application Oc ber 1., 1940, Serial No. 360,545

' (Cl. its-s41) 8 Claims. The invention relates to electromagnets and is r particularly applicable to electromagnets which are to respond rapidly and which reciprocate through a relatively short distance.

An object oi the invention is to provide an electromagnet which quickly responds to the energization and deenergization thereof. Another object is to provide an electromagnet which is highly eflicient when energized for short periods.

Another object is to provide an electromagnet which requires a. relatively small amount of energy for establishment of a given flux therein.

Another object is to provide a short stroke magnet having a relatively high pull.

Another object is to provide an electromagnet having a small mass which must be accelerated upon its response.

Another object is to provide an electromagnet which has a relatively low inductance.

Other objects and advantages will hereinafter appear. a

The accompanying drawing is illustrative of an embodiment; of the invention.

In the drawing Fig. 1 is a side view of the electromagnetic frame embodying the invention.

Figs. 2 and 3 show somewhat diagrammatically difierent positions of the movable armature of the electi'omagnet relatively the stationary polar member, the lower part of each resenting one-half of the width oi the stationary polar member, while upper part repress one-half the width of the armature move. s polar monster, both in a plane pareliel to the laminations.

Fig. 4 is a cross section through a magnet along the lines t t oi Fig. 1, while Fig. 5 is a detail showing of the flux distribution for a given position of movable polar member or plunger.

Figs. 6 and 7 are fragmentary cross sections along the lines 56 and 1-1, respectively, of Fig. 2.

Referring to the drawing the electromagnet which is of the solenoid type comprises a core, shown more in detail in Figs. 4, 6 and 7, consisting of a number of spaced laminated non-magnetic strips or units 5 which are rigidly attached to a top member 2, comprising a multiplicity of magnetizable laminations 2a and 2b, respectively, of a magnet frame or yoke. The elements I of said core extend axially between the top member 2 and a bottom member 3 of said yoke. The bottom member 3 comprises a multiplicity of magnetic or an magnetizable laminations la and lb, respectively. The strips I are interleaved with the laminations of the top member 2, as shown in Fig. 6, and are fastened thereto by means of rivets i. The magnet yoke is arranged symmetrically with respect to the core, and the top and bottom members thereoi' are joined by side members I-l, which are also composed of laminations of magnetic material.

Rectangular openings 3 are cut out of the strips 5 at equal distances from each other along the entire lengths! said strips, the distance between the individuai openings being somewhat less than the axial oi the openings. The openings t have magnetic inserts to equal in thickness to that of the respective strip, so that the strips 5 present a smooth slidin" surface.

'Eihe is pro deal with a. reciprocable piunger comprising a locality of spaced nonhic' are also arother and 5, e latter. The strips & 1' lower ends by means i a pair oi 1; :hdinally are joined eti'ier a ivets it. oiurality s of the having magno central core, comprising the stationary s 5 and "the slidabie armature comprising the s 8, surrounded an energ zing coil 4 in most manner. The terminations of the rective side members i, and of the top and botmembers 2:: and 2b, and 3a and 3?) have their intermediate portions rigidly connected by rivets it, whereas the overlapped ends of the respective members are joined'by rivets i2, atth'e corners said yoke, thus providing a rigid frame;

it will be noted from Fig. 6 that the laminationsla are arranged so that they abut the side edges of the strips 5, while the laminations 2b extend through the central portion of the mem ber 2 to provide for the proper spacing of the strips 5. Similarly the laminations 3a. are of such length that they abut the side edges of the movable strips U, while the laminations 3b extend across the center of the member 3 to pro- 2 yide,v in combination with the alternate members and the la, openings for the passage of the strips 8.

The approximate path of the magnetic flux between the inserts la of the central core strips 5 inserts Illa ofthe plunger strips 8 have been indicated by the lines I of the fragmentary diagram Fig. 5, while the paths of the lines of force through the entire central part of the electromagnet are also indicated diagrammatically by the curved lines I in Figs. 2, 3 and 4.

From this it will be seen that the air gaps of the magnetic field of the core are connected in series, while the pull exerted by the magnetic flux on the various magnetizable elements of the movable core acts .in parallel, that is the total pull on the armature is the sum of the pulls between the individual magnetic elements. As a result the magnet is capable of exerting on the movable armature a pull which for a given mass of magnetic material and for a given excitation is greatly in excess of that obtained by a conventional magnet. Thus a magnet with an effective cross sectional area of approximately square inch exerts a force of 50 pounds over a maximum distance of %4 of an inch, while the actual weight of the plunger is approximately 2 ounces. It is thus apparent that a magnet in accordance with the present design yields for a given weight and a given excitation a pull which .over short distances is much greater than that ofmagnets of conventional design. Furthermore in view of the fact that the magnetic mass which has to be energized to produce the magnetic field and the resultant pull is relatively small, the time constant of such magnet is also reduced, so that the magnet responds very quickly upon the closure of the energizing circuit, with the further result that the efliciency of the magnet in performing a certain amount of work is relatively high.

While the foregoing description and the drawing show a solenoid type of reciprocating magnet it is obvious that the principle of the design may also be adapted to other mechanical devices in which for instance the armature has an angular rather thana reciprocating motion relative.

to the stationary pole. Other modifications will be obvious to those skilled in the art.

What I claim as new and desire to secure by Letters Patent is:

1. An electromagnet comprising two cooperative elongated polar members movable relatively in' the direction of their major axis, and'a magnetizing winding adapted to induce a magnetic flux in the direction of said axis, each of said members comprising a plurality of substantially similar units spaced apart from each other transversely to said axis and the units of one member alternating with the units of the other member, each unit comprising a non-magnetic solid support and a plurality of similar magnetic elements attached to said support and spaced from each other in the direction of said axis.

2. An electromagnet comprising a magnetizable frame, a winding adapted to induce in said frame a magnetic flux terminating in spaced magnetic poles of opposite polarity, two, cooperative elongated polar members movable relatively in the direction of their major axis and arranged with their major axis between said poles of opposite polarity, each of said members comprising a plurality of substantially similar units spaced apart from each other transversely to said axis and the units of one member alternating with the units of the other member, each unit comprising with their major similar magnetic elements attached to said support and spaced from each-other in the direction of said axis.

3. An electromagnet comprisingan energizing winding, two cooperative members arranged magnetic field induced by said winding and movable relatively in the direction of said axis, each of said members comprising a plurality of substantially similar units spaced apart from each other transversely to said axis, and the units of one member alternating with the units of the other member, each unit comprising a non-magnetic solid support and a plurality of similar magnetic elements attached to said support and spaced from each other in the direction of said axis.

4. A short stroke electromagnet having a relatively high pull, comprising an energizing winding, a frame composed of magnetic materialassociated with said winding to provide a path for the magnetic flux induced by the latter, two cooperative polar members associated with said frame, one of said polar members being fixed to said frame and the other polar member being movable relatively to said frame and said first polar member, each ofsaid polar members'belng composed of a plurality of spaced parallel strips, each of said strips being composed of non-magnetic material and each carrying a plurality of like elements of magnetic material fixedly spaced apart from each other in the direction of the length of the strip, and the strips of the two polar members being interleaved, whereby the strips of the movable polar member are relatively movable in the spaces between the strips ofsaid fixed polar member.

'5. A short stroke electromagnet having a relatively high pull, comprising an energizing winding, a frame composed of magnetic material associated with said winding to provide a path for the magnetic flux induced by the latter, two cooperative polar members associated with said frame, one of said polar members being fixed to said frame and the other polar member being movable relatively to said frame and said first polar member, each of said polar members being composed of a plurality of spaced parallel strips, each of said strips being composed of non-magnetic material and each carrying a plurality of like elements of magnetic material fixedly spaced apart like distances from each other in the direction .of the'length of the strip, the strips of the two polar members being interleaved, whereby the strips of the movable polar member are relatively movable in the spaces between the strips of said fixed polar member, and the distance between the a non-magnetic solid support and a plurality of respective elements of each strip being less than the dimensions of each element axially of said winding, for the purpose set forth.

6. An electromagnet comprising an energizing winding, two cooperative polar members arranged with their major axis in the direction of the magnetic field induced by said winding and movable relatively in the directional said axis, a magnetizable frame arranged to complete the magnetic circuit for the flux induced in said polar members, each of said members comprising a plurality of substantially similar units spaced apart from each other transversely to said axis and the units of one member alternating with the units of the other member, each unit comprising a non-magnetic solid support and a plu-' rality of similar magnetic elements attached to axis in the direction of the 8. An electromagnet comprising an energizingsaid support and spaced from each other in the direction of said axis.

7. An electromagnet comprising a magnetizabie frame, a winding adapted to induce in said frame a magnetic flux, said frame terminating in spaced magnetic poles of opposite polarity, two cooperative elongated polar members movable relatively in the direction of their major axis and arranged with their major axis between said poles of opposite polarity, each polar member being composed of a plurality of spaced flat parallel strips each comprising a non-magnetic frame and a plurality of magnetizable elements fixedly spaced apart from each other in the direction of said axis, and strips of the two polar members being interleaved, whereby the strips of each are relatively movable in the spaces between the strips of the other.

winding, two cooperative polar members surrounded by said winding, a magnetizable frame surrounding said winding and forming a return path for the magnetic flux induced thereby, one of said polar members being fixed to said frame and the other polar member being movable rectilinearly relatively to said frame and said first polar member, each polar member being composed of a plurality of spaced flat parallel strips each comprising a non-magnetic frame and a plurality of magnetizable inserts fixedly spaced apart from each other in the direction of the axis of the winding, and the strips of the two polar members being interleaved, whereby the strips of each are relatively movable in the spaces between the strips of the other.

MARION R. WINKLER. i 

